SpectraLink NetLink Wireless Telephones Best Practices White Paper Wireless Telephone - Manual (Page 5)

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and provides consistent coverage.
2.2.1 Site Surveys Performing a site survey can minimize the possibility of dead spots. The
AP equipment provider can usually perform a site survey. While many
tools exist that allow customers to perform their own assessment,
SpectraLink recommends that every site employ a professional site
survey to ensure optimum coverage and minimize interference.
Site surveys are a necessity for large or complex facilities. An extensive
site survey will ensure that the minimum number of APs are deployed,
but at the risk of having to significantly reconfigure the network if the
coverage area is remodeled. Wi-Fi infrastructure providers are making
significant developments to reduce the time, cost, and complexity of
determining AP locations. Because the cost of APs has significantly
dropped over the last few years, in some cases it is more cost effective
to install more APs with overlapping coverage rather than try to
maximize coverage for each AP with a rigorous site survey.
To verify coverage with an existing Wi-Fi network, NetLink Wireless
Telephones offer a site survey mode that can be used to test the AP’s
signal strength in the wireless LAN coverage area. This mode detects
the four strongest AP signals and displays the signal strength and the
AP channel assignments. This mode can be used to detect areas with
poor coverage or interfering channels. With the NetLink e340 and i640
Wireless Telephones, the entire coverage area should be checked to
ensure that at least one access point’s reading is stronger than –70 dBm
in all areas. Also, if the site survey mode indicates 2 APs using the
same channel, then at least one other AP must be indicated at 10 dBm
stronger than those APs to avoid channel conflicts. After a site survey is
completed, coverage issues can be resolved by adding and/or relocating
APs and overlap issues may be resolved by reassigning channels or by
relocating some access points. Another complete site survey should be
performed after any adjustments are made to ensure that the changes
are satisfactory and have not impacted other areas.
2.2.2 Access Point
Data Rates and
Power Output
All APs on the wireless network used by the NetLink Wireless
Telephones must be set to the same supported and basic data rates. If
this is not adhered to, the NetLink Wireless Telephones may not
associate to the closest AP if a more distant one supports a higher data
rate.
In addition, all APs must be set to operate at the same power output.
SpectraLink highly recommends a power output setting of 100 mW. If
this cannot be accommodated, SpectraLink recommends a 50 mW
setting and requires a minimum of 30 mW. With lower power output
settings, special attention must be made to AP placement to ensure
there are no frequency re-use issues. These problems may not be
evident when using the handset’s site survey tool as it is assumes 100
mW transmission power from the APs.